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Bald Eagle

The Bald Eagle (Haliaeetus leucocephalus) is a bird of prey native to North America. It is most recognizable as the national bird of the United States. This species was near extinction late in the 20th century but has since recovered and now has a stable population. Because of this it is in the process of being removed from the U.S. federal government’s list of endangered species.

The distinctive appearance of the adult’s head is the reason for this bird’s common and scientific names. Bald in the English name refers to the white head feathers, and the scientific name is derived from Haliaeetus, the New Latin for “sea eagle,” (from the Greek haliaetos) and leucocephalus, the Greek for “white head,” from leukos (“white”) and kephale (“head”).

Range and habitat

Bald Eagles can be found in small concentrations throughout the U.S. and Canada, usually near large bodies of water. Alaska has the distinction of having the largest population of Bald Eagles; currently out of the estimated 100,000 Bald Eagles on Earth, half live in Alaska.

Description

Juvenile birds have speckled brown plumage all over, the distinctive head and body plumage arriving 2-3 years later before reaching sexual maturity. Adult females have a wingspan of approximately 7 feet (2.1 meters); adult males are slightly smaller and have a wingspan of 6 feet, 6 inches (2 meters). Adult females weigh approximately 12.8 lb (5.8 kg); males weigh 9 lb (4.1 kg).

They are protected by three federal laws:

  • the eagle law, which protects bald and golden eagles
  • the migratory bird act
  • and the endangered species list (up until February 13, 2006 when they were removed)

Behavior

Bald Eagles build huge nest platforms out of branches, usually in large trees, adding fresh new material each year. After several years, the nest may weigh upwards of a thousand pounds or more. Pairs are monogamous and mate for life.

Bald Eagles old enough to nest often return to the area in which they were raised. They are more social than many other raptor species: an adult bald eagle looking for a nesting site is more likely to select a location that contains otherjuvenile eagles than one with no eagle population.

Bald Eagles are powerful fliers and can ride thermal convection currents to range far and wide.

They have a long lifespan, with some birds in captivity living to be 60 years old.

They do not scream as often shown on television. Usually the call of a red-tailed hawk is placed over the image of a flying eagle. They sqeak and have a shrill cry, punctuated by grunts.

Reproduction

Bald Eagles reach sexual maturity at 4 or 5 years of age. Mated pairs produce between one and three eggs per year, but it is rare for all three chicks to successfully fledge. Third chicks are often removed from nests to use in reintroduction programs in areas where the species has died out.

In such programs, the hatchlings are raised in boxes placed on platforms in the tree canopy. They are fed in such a way that they cannot actually see the person supplying their food, until they are old enough to fly and find their own food.

Diet

The Bald Eagle’s diet is diverse and includes carrion, fish, smaller birds, rodents, and sometimes food scavenged or stolen from campsites and picnics. When hunting the eagle swoops down over the water and snatches the fish out of the water with its claws. They eat by holding the fish in one claw and tearing the flesh with the other. Eagles have structures on their toes called spiricules that allow them to grasp fish. Osprey also have this particular adaptation.

This method of fishing can be dangerous. If the fish is too heavy, the eagle will be dragged into the water. It may swim to safety, but some eagles drown or succumb to hypothermia.

Rare vagrant

This species has been reported once in Ireland. The exhausted specimen was discovered by a national parks worker in a northern heath. It is believed that a storm blew it out to sea, and the bird struggled across the Atlantic Ocean.

Bald Eagle


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